Spiral-finned tubing and method of making same



Nov. 5, 1929. H. w. BUND Y SPIRAL FINNED TUBING AND METHOD OF MAKINGSAME 2 Sheets-Sheet 1 Fil ed June 20, 1927 INVENTOR. "ZanZ y A TTORNE Y.I

Nov. 5, 1929.. H. W. BUNDY SPIRAL FINNED TUI BING AND METHOD OF MAKINGSAME Filed June 20, 1927 2 Sheets-Sheet .2

R I Q I NVEN TOR. 17%??? Zandy Y K M A TTORNEY.

m Z QN ME I? stars I HARRY W. BUNDY, OF DETROIT, MICHIGAN, ASSIGNOR, BYMESNE ASSIGNMENTS, TO BUNDY TUBING COMPANY, OF DETROIT, MICHIGAN, A.CORPORATION OF MICHIGAN SPIRAL-FINNED 'ronmo'nnn METHOD or MAKING salsaApplication filed June 20,

This invention relates to spiral finned tubing and method .of makingsame which 1s useful for the dissipation of heat, as for example inmechanical refrigeration devices,

radiators for automobiles, and the like.

Finned tubing is old in the art, and various ways have been proposed forwinding fin stock on a preformed tube. Also spiral tubing is old; or in'other words, tubing made of w flat strip stock wound spirally in theform of a tube with the edges of the convolutions secured together insome manner.

The present invent'on contemplates a method of making finned tubing'byspirally winding flat stri stock, and at the same time .shaping the stoc'so'that fins are formed on the tube as the same is made.

Fig. 1 is an assembly view showing the method of making the tubing.

Fig. 2 is a detail of the stock forming and crimping mechanism.

Fig. 3 is a sectional view on line 3-3 of Fig. 1 showing some of therollers which aid in the forming of the tube.

Fig. 4 is a sectional view taken on line 4-4; of Fig. 2 showing rollswhich are suitable for shaping the stockprior to its being wound into atube. Fig. 5 is a longitudinal vertical sectional view taken through aset of rolls on the mechanism shown in Fig. 1 and showing how theserolls finally form the tube.

Fig. 6 is a sectional view section of completed tubing.

Fig. 7 is a sectional view on Fig. 6.

The method consists in drawing flat strip stock from a supply roll (notshown). The strip stock, after leaving the supply roll, may

be drawn over a roller l through an acid bath 2, and from here the stripstock passes upwardly over a roller 3, and then downwardly over rollers4 in a solder bath 5, to thus tin or apply a coating of solder tothestock.

The solder in the bath is kept in a molten condition by suitable burners6. The strip stock'may then be drawn over the roller 7 and then througha cooling water bath 8 over roller 9.

As thus far described, ordinary trip stock taken through a line -7- 7 of1927. Serial No. 200,273.

made of copper or other desirable material maybe used, and it is tinnedin the manner described immediately before it is acted upon to be formedinto a finned tube. However, if desirable, the strip stock can bepreviously tinned, so that it can be drawn from a supply roll directlyto the forming mechanism. Either procedure may be followed to meet theparticular requirements, although it is thought to be preferable to tinthe stock just prior to its being formed into tubing.

' However, the strip. stock thus tinned, or if it has been previouslytinned, it is ready to be formed into tubing. The stock is drawn overthe guide roller 10 which is positioned at an angle to give the stock atwist or turn of approximately ninety degrees. The stock is then drawnthrough a set of shaping rollers 11. These shaping rollers may take theform shown in Fig. 4, and consist of coacting rollers 11 and 11 drivenby gears through a shaft 12, and which shape the stock into angle form,as shown in Fig.,4=.- The angle form has a portion 13 whichbecomes thefin, and a portion l l which is spirally wound to form the body of thetube. The stock thus angularly formed is drawn through a guiding die '15located immediately adjacent the winding mechanism, and for thepurposeof guiding and holding the stock in proper position with respectto suchmechanism.

For the purpose of spirally winding the stock, there is provided aspinning arbor 20 rotated by a suitable mechanism, as by means of apulley 21 and belt 22. The stock is wound upon the spinning arbor inspiral form and it will be understood that it is desirable,

and in some cases necessary, to crimp the portion '13 of the stock inorder that the stock can be nicely woundin this manner. For this purposea pair of interengaging crimping rollers 23 and 24 are provided, and oneof which is suitably mounted on a shaft and driven by suitable 1means,as at 25. These crimping rollers are well known to those familiar withthe art to crimp or corrugate the stock to expedite the step of windingit.

The spinning arborand crimping rollers are rotated with proper relativespeeds and the stock is spirally -wound upon the arbor,

engage between the fins of the tubing. The

rollers are preferably power-driven as by portion, and then bycompressing the-conthrough asolder that the wall of the tube is and inthe first instance takes the form as shown at the right-hand side ofFig. 5. The tube-forming portion 14 of each convolution overlaps,substantially half way, the adja cent convolution, as will be seen byinspection of Fig. 5. The tube passes from right to left through a setof rollers 26. There are, preferably, three of these rollers, as will beseen in Fig. 3, referenced 26, 26 and 26, and each roller is in the formof a Worm so as to means of a gear wheel 27 idler 28, and may be keyedrollers function to draw or move the tube lengthwise. These rollers arearranged to compress the tube against the spinning arbor thus to form anofiset in each portion 14.. By overlapping each portion 14 substantiallyhalf way with respect to the next adjacent and an interposed volutionsagainst the arbor it will be seen formed of a double thicknessthroughout.

With the tube thus formed it is sealed by further application of solder.pose a suitable fluxing acid is applied by means of a conduit 30 andthen the tube goes applying device. This may take the form of apct 30holding solder which is kept molten by burners 31 and which includes anautomatic solder lift 32. The solder lift 32 is rotated by suitablemeans in bearings 33, and includes a solder lifting device for raisingthe molten solder and pouring it over the tube. The details of thesolder lifting device are not essential to the present method, as anysuitable structure can be used. However, an example of such a device 1s.

shown in my Patent #1,605,326, granted November 2, 1926.

Inasmuch as thestockis tinned before it is wound, either by a tinningoperation immediately preceding the winding operation. or by a previoustinning operation, the tube can be sweated together by merely advancingit through a heated zone, for melting the coating'of tin or solder andcausing all parts of the tube to thus adhere together. However, it isthought preferable to apply additional solder as just described.

As the tube leaves the solder applying device 32 the excess moltensolder maybe remox'ed by applying a stream of air against the tube bymeans of the nozzle device 34..

Following this operation, the tube may be cooled by passing the samethrough a, water chamber 35 which is supplied with cold water by conduit36 whichwater is-permittedto drain off through the drain 37. In order toaid in the advancing of the tube, a second set of rollers 38, similar tothe set of rollers 26, may be used. These rollers are also preferablypower-driven and'may also 'press the tube to insure final and correctshaping of to shafts 29. These.

For this pur- 'liable to become loose;

with the tube the heat within the tube, or the enced 14; by the thetube. For this purpose the arbor 20 may take the form of a floatingarbor and have its free end extending entirely through'the device so asto lie within the tube at the point where the rollers 38 press againstit.

By this method a spirally wound tube with a double .wall and integralfins is made in a continuous length. 'As the .formed tube emerges fromthe forming mechanism it may be cut into desired lengths either by anautomatic or a hand operated cut-01f. It is thought to be preferable tomake the tube with the spiral convolutions overlapped in the mannerdescribed to provide a tube of a double wall. However, the invention isnot intended to be limited to this sortof tube, and the inventioncontemplates the making of a tube wherein the wall is not of a doublethickness throughout as a tube of this nature may not be required in allplaces. For example, in some uses the strength of the tube may not beimportant so that the double wall is not essential, and a tube can bemade by the method wherein the overlap of the convolutions is justsufficient to secure adjacent convolutions together.

Thus a spirally wound finned tube can be made in continuous lengths froma single supply of flat strip stock. Due to the fact that the tube isprovided with a double wall it .has considerable strength, and also thethickness of the stock can be varied. The fins are inegral with the Wallof the tube and are not and being integral heat in the material orliquid within the tube is efficiently conducted-to the fins Where theheat is dissipated by radiation, or vice versa Where the material in thetube is to be heated instead of cooled.

i In the claims appended hereto the terms iorizontal portion and uprightportion of the stock are utilized; by the term horizontal portion ismeant the portion referupright' portion is meant that referenced 13. Byusing these terms it is not intended that the two portions of the stock,after the same is bent, be perpendicular to each other, for it iswithinthe invention to have the upright portion at an angle to thehorizontal portion which is other than a right angle so that in thefinished tube right portion rojecting outwardly from the body of the tue to form an integral spiral fin on the tube, and then compressing theoverlapped convolutions together.

2. The method of making spiral-finned tubing, which consists in drawingflat strip stock from a supply, turning up one edge of the stock to forman upright portion leaving a horizontal portion, spirally winding thethus-formed stock with the adjacent convolutions of the horizontalportion overlapped to form the body of the tube, right body fin on thetube, compressing the overlapped convolutions together, and thenfinishing the tube by the application of solder to cause theconvolutions to adhere together.

3'. The method of making spiral-finned tubing, which consists in drawingflat strip stock f om a supply, bending the stock longitudinaltly toform an upright portion and to leave a substantially horizontal portion,winding the stock spirally, overlapping each convolution of thehorizontal portion subportion projecting outwardly from the and with theup of thetube to form an integral spiral together.

8. A tube with a helical fin, which includes a tubular body foamed by ahelically wound angular strip stoc each convolution of one the angleoverlapping substantially a leg of the angle overlapping substantially apart ofthe next adjacent convolution of the same leg of the angle toform a continuous double wall for the tube and the other leg of theangle forming a continuous helical fin.

In testimony whereof I'aflix m signature.

HARRY W. UNDY.

stantially one-halfthe distance of the adjacent convolution, compressingthe overlapped convolutions to form the body of the tube with theupright portlon forming an integral spiral fin on the tube. j 4. 'Themethod of making spiral-finned tubing, which consists in drawing fiatstrip stock from a supply, bending the stock longitudinally to form anupright portion leaving a horizontal portion, spirally winding the stockover an arbor with the convolutions of the horizontal portionoverlapping and forming the bod upright portion orming a continuousspiral fin around the tube, passing the tube lengthwise with continuousmovement, and applying solder thereto to connect the convolutionstogether.

5. The method of forming a tube consisting in rolling a strip offlat,thin material to provide a laterally extending flange and then rollingthe strip spirally on a mandrel having the ed es of succeeding windingsoverla ping the e ges of previous windings wit the flange projectingradially and spirally directed of the periphery.

6. A spiral finned tube which includes a tubular body stock formed intoan with portions angular cross section angle projecting outwardly toform a spiral fin, the overlapping portions of the strip stockbeingpressed together to make the body 'of uniform double thickness, thestock of the overlapped leg being slightly ofiset toform a of the tubeand with the formed by spirally wound strip of one of the legs of theangle overlapped and with the other leg of the-

